| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hot-rolled steel strip manufacturing method and a hot-rolled steel strip manufacturing facility for stably manufacturing a hot-rolled steel strip having superfine ferritic structure over the total length of a coil without degrading the thickness profile and strip shape. <P>SOLUTION: Finish rolling is performed so that the steel strip temperature immediately after the finish rolling is substantially constant equal to or above the Ar<SB>3</SB>transformation point over the total length of the steel strip, the steel strip is cooled to the temperature equal to or below the Ar<SB>1</SB>transformation point immediately thereafter, successively heated to the temperature equal to or above the Ac<SB>3</SB>transformation point to induce the reverse transformation to austenite, and immediately cooled to the temperature equal to or below the Ar<SB>1</SB>transformation point. The steel strip immediately after the finish rolling and the heating is preferably cooled at a cooling rate of≥50°C/second, the temperature of a rough bar before the finish rolling is set to be substantially constant over the total length, and the finish rolling speed is preferably substantially constant over the total length. <P>COPYRIGHT: (C)2004,JPO</p> |
